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NASA Announces Discovery of 30-Year-Old Black Hole
broknstrngz tips news of an announcement today from NASA about the discovery of a black hole in the M100 galaxy, roughly 50 million light-years from Earth. The discovery is notable because, if confirmed, it's now the youngest known black hole, born from the remains of a supernova we observed in 1979. Bad Astronomer Phil Plait explains why scientists think it collapsed to a black hole, rather than a neutron star: "The way a neutron star emits X-rays is different than that of a black hole. As a neutron star cools, the X-ray emission will fade. However, a black hole blasts out X-rays as material falls in; that stuff forms a flat disk, called an accretion disk, around the black hole. As this matter falls onto the newly created black hole, it gets heated to unimaginable temperatures — millions of degrees — and blasts out X-rays. In that case, the X-rays emitted would be steady over time. What astronomers have found is that the X-rays from SN1979c have been steady in brightness over observations from 1995 – 2007. This is very strong evidence that the star’s core did indeed collapse into a black hole." He also warns that we're not certain quite yet, and we'll have to keep our eye on it to make sure it's not a pulsar.
We use the European version of "discover", it's new when it's new to us :)
Live today, because you never know what tomorrow brings
To all the inevitable pedantic responses about it not "really" happening 30 years old, I'll be even more pedantic. :) Relativity of Simultaneity, look it up. It's absolutely meaningless to talk of the temporal ordering of space-like separated events. In some suitable reference frame, it "really" did happen 30 years ago.
Of course. Unless you have some magical way of getting those images to us or us to the black hole faster than the speed of light, for all intents and purposes it is 30 years old, as viewed from our frame of reference.
It's not that hard to figure out. We're looking at what a 30-year old black hole looks like, regardless of how long it took that light to get here.
"Our two-party system is like a bowl of shit looking at itself in a mirror." - Lewis Black
From our point in space, it is 30 years old.
But, more to the point, what we're observing now is a 30-year-old black hole. It's just that over where the black hole is, it's no longer 30 years old. That's not particularly relevant to us on Earth.
"No, it's 50,000,030 years old no matter where you are."
Uhm. I'm moving at 0.8c. It looks very much like 25000015 years old to me.
Are you suggesting that there's a global frame of reference?
Why does *our frame* matter so?
Because it's the one we're observing it from. In a Relativistic universe, everything is relative to a frame of reference and you can't actually say anything about when things happen or their age outside of the context of a specific frame of reference.
The enemies of Democracy are
There's an obvious universal frame of reference: measure everything relative to the place where the big bang happened. Your choice of axes is somewhat arbitrary, though.
This is a common misunderstanding of the big bang theory.
There is no center. It didn't start at a "location". The entire universe is evenly expanding, from everywhere.
They common analogy is to reduce the 3D space of the universe to a 2D example. Imagine two points on the 2D surface of a balloon. One point is you ("the observer"), the other point is something distant, like a star, that you are observing. Now inflate the balloon. The result is that the two points move apart, because space (the rubber of the balloon) is expanding. A line drawn between the two points would be longer and longer. Note that neither point is "special". Both points observe the same symmetric effect: the other point moving away.
The real universe is a lot like this, except instead of a 2D surface expanding, it's a 3D volume expanding. There's no "center", all of the points move away from each other. From the point of view of each observer, they are the center.
More accurately speaking, each observer is the center of their own private spherical "observable" universe expanding away from them. The center of the universe is your own head. 8)
"Are you suggesting that there's a global frame of reference?"
No, but he could argue that there's in fact a *privileged* frame of reference with regards of age: the one centered on the object to be dated.
He could argue, and argue and argue, that there really is a *privileged* frame of reference with regards of age; but, I'm not letting my daughter ("the object to be dated") out of sight of my shotgun.
I feel fantastic, and I'm still alive.
As this matter falls onto the newly created black hole, it gets heated to unimaginable temperatures — millions of degrees— and blasts out X-rays
Translation: The temperature is so high, it is somehow unimaginable using numbers. But since you are reading on, let me just pull a totally random number out of my ass and say a million degrees... wait no.. make it a millions, as in more than 1 million, which makes my claim sound sorta vague and not precise but makes it nevertheless appear I know what I'm talking about. That should cover the unimaginable bit of it. Besides, its not like you're going to check anyways so fuck it, lets and some em dashes for extra emphasis for no other reason other than because its really "HOT". I mean wow, can you imagine a place this hot? I'm just siting here in my office, thinking to myself, geeze this black hole stuff is not the usual environment I'm used to, most likely because I would have been obliterated and spit out as really "HOT" x-rays... there, you see where I'm coming from? HOT!
~ In Trust, We Trust ~
It is correct to say that an accretion disk can form around a neutron star as well.
The distinguishing characteristic is that a neutron star bigger than its Schwarzschild radius. Not just a little bit bigger, but at least 11% bigger [see the Buchdahl-Bondi limit; this a theoretical limit for any perfect fluid spheres -- actual neutron stars don't come close to saturating that bound]. This means that the accretion of charged particles that is spiraling inward will eventually hit the surface, stopping the charged particles very rapidly. The radiation from suddenly stopping charged particles (Bremsstrahlung) is fairly distinctive, and is not seen here.
By contrast, an accretion disk around a black hole loses energy and eventually passes through the horizon. There is no sudden breaking and hence no Bremsstrahlung radiation It is the accretion disk and the lack of Bremsstrahlung that convinces us that the most likely candidate is a black hole.
[The reason the size limit was important is that as you get close to the horizon, redshifting makes things harder to see anyway. The point of the Buchdahl-Bondi theorem is that any perfect fluid sphere has to be about 11% bigger than the size of a black hole of equivalent mass. This limits the total redshift due to the object to a modest factor of 2, ensuring for a large class of matter (including neutron stars and all known matter to date) that the collision with the surface if it existed would be visible. This does not prevent unknown matter with exotic properties having s surface that is beyond the event horizon but close enough in the we would not see the Bremsstrahlung radition, but it is very difficult to construct "reasonable" solutions.]
Actually, there exists a well defined frame of reference with respect to velocity. In rotation this is pretty obvious, since rotation with respect to the absolute frame causes centrifugal forces to appear.
Constant linear movement is not so easy to measure, but there's the background radiation dipole that can be measured and defines an absolute velocity with respect to the universe.
We cannot define one point as an absolute origin, but we can define one state as being "standing still" with respect to the absolute origin, both in rotation and in translation.